Alkaline earth metal and zinc hydroxy(substituted)acetate complexes and alkaline earth metal glyoxylate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

assessment report

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

315 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Test concentrations of 50 and 100 mg/L caused moderate inhibition of algae growth after 72 h. The test concentrations 1250, 2500, 5000 and 10000 mg/L resulted in total inhibition after 72 h.

Results with reference substance (positive control):

no reference substance (positive control) was tested.

Reported statistics and error estimates:

no data available

Validity criteria fulfilled:

yes

Conclusions:

The test item is not acute toxic to algae.

Executive summary:

The substance was tested in a study following OECD Guideline 201 and GLP. It is not acute toxic to algae.

E_bC₅₀(72h)= 300 mg/l;

E_rC₅₀( 72h) = 315 mg/l

The source substance contains the major organic moieties of the target substance. Therefore, this study shows that no toxicity to algae can be attributed to the organic moieties of the target substance.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

assessment report

Key result

Duration:

72 h

Dose descriptor:

IC50

Effect conc.:

0.55 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

IC10

Effect conc.:

0.17 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.27 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.12 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

The target substance contains 16.5 % Zn ions. Therefore, the hazard value for Zn ion is converted to the target substance considering a Zn content of 16.5 %.

IC50 (Zn ion) = 0.11 mg/L

IC 50 (target substance) = 0.11/0.165 = 0.55 mg/L

IC10 (Zn ion) = 0.028 mg/L

IC 10 (target substance) = 0.028/0.165 = 0.17 mg/L

LOEC (Zn ion) = 0.044 mg/L

LOEC (target substance) = 0.044/0.165 = 0.27 mg/L

NOEC (Zn ion) = 0.02 mg/L

NOEC (target substance) = 0.02/0.165 = 0.12 mg/L

Conclusions:

The Chlorella sp. culture acclimated to copper had no increased zinc tolerance compared with that of the nonacclimated algae, nor were there any changes in control growth rates. The IC50 of the non-acclimated culture was 110 µg Zn/L, whereas the culture acclimated to 2 µg Cu/L for 82 days showed an IC50 value of 98 µg Zn/L. The LOEC and NOEC for the non acclimated algae was 44 and 20 µg Zn/L, respectively. This result is also relevant for the target substance, which contains 16.5 % zinc ions.

Executive summary:

Chlorella sp.was acclimated in medium containing 2 µg Cu/L for 100 days. Changes in algal growth rates and copper and zinc tolerance were monitored using standard growth inhibition toxicity tests in minimal medium over 72 h. The acclimated Chlorella sp. culture had no increased zinc tolerance compared with that of the nonacclimated algae, nor were there any changes in control growth rates. The IC50 of the non-acclimated culture was 110 µg Zn/L, whereas the culture acclimated to 2 µg Cu/L for 82 days showed an IC50 value of 98 µg Zn/L. The LOEC and NOEC for the non acclimated algae was 44 and 20 µg Zn/L, respectively. This result is also relevant for the target substance, which contains 16.5 % zinc ions. Converted to the target substance under consideration of the zinc content of 16.5 %, the IC50 value is 0.55 mg/L, IC10 value is 0.17 mg/L, LOEC is 0.27 mg/L and the NOEC is 0.12 mg/L.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

assessment report

Duration:

72 h

Dose descriptor:

EC50

Remarks:

pH 5.7, DOC 6.28 mg/L, Ca 3.45 mg/L

Effect conc.:

12.42 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Remarks:

pH 8.01, DOC 5.89 mg/L, Ca 65.4 mg/L

Effect conc.:

0.64 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Remarks:

pH 7.42, DOC 22.3 mg/L, Ca 43.4 mg/L

Effect conc.:

5.22 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

The target substance contains 16.5 % Zn ions. Therefore, the hazard value for Zn ion is converted to the target substance considering a Zn content of 16.5 %.

EC50 (Zn ion) = 0.106 mg/L

EC 50 (target substance) = 0.106/016.5 = 0.53 mg/L

EC50 (Zn ion) = 0.861 mg/L

EC 50 (target substance) = 0.861/0.165 = 4.305 mg/L

EC50 (Zn ion) = 2.05 mg/L

EC 50 (target substance) = 2.05/0.165 = 10.25 mg/L

Conclusions:

An increase in Ca, Mg, and Na concentraion and pH value had protective effects on the zinc toxicity. Among these factors, the pH had the most significant effect. Both inorganic and organic Zn complexation reduces Zn2+ activity and thus also reduce toxicity. Inorganic complexation (i.e. ZnCO3) is relatively straightforward, while dissolved organic matter (DOM) vary much in their zinc-binding characteristics. This result is also relevant for the target substance, which contains 16.5 % zinc ions. The EC50 values converted to the target substance range between 0.64 and 12.42 mg/L depending on the pH and DOC content.

Executive summary:

Zinc toxicity to a green alga (Pseudokirchneriella subcapitata) was evaluated in a series of experiments with spiked natural surface waters. The eight selected freshwater samples had varying levels of bioavailability modifying parameters: pH (5.7–8.4), dissolved organic carbon (DOC, 2.48–22.9 mg/L), Ca (1.5–80 mg/L), Mg (0.79–18 mg/L), and Na (3.8–120 mg/L). In those waters, chronic zinc toxicity (expressed as 10% effective concentrations [EC10]) varied up to 20-fold for the alga (72-h EC10 from 27.3 to 563 mg Zn/L). An increase in Ca, Mg, and Na concentraion and pH value had protective effects on the zinc toxicity, whereas the pH had the most significant effect. Both inorganic and organic Zn complexation reduces Zn2+ activity and thus also reduce toxicity. Inorganic complexation (i. e. ZnCO3) is relatively straightforward, while dissolved organic matter (DOM) vary much in their zinc-binding characteristics. This result is also relevant for the target substance, which contains 16.5 % zinc ions. The EC50 values converted to the target substance range between 0.64 and 12.42 mg/L depending on the pH and DOC content.

Description of key information

Read-Across: WoE, FF6, D. subspicatus, OECD 201, GLP, 72 h, E_rC50 = 315 mg/l

Read-Across: WoE, Zn, P. subcapitata, 72 h, E_rC50 = 0.64 mg/L, 5.22 mg/L, 12.42 mg/L (values converted to the target substance considering the Zn content of 16.5 %)

Read-across: WoE, Zn, Chlorella sp., 72 h, E_rC50 = 0.55 mg/L, E_rC10 = 0.17 mg/L, LOEC = 0.27 mg/L, NOEC = 0.12 mg/L (values converted to the target substance considering the Zn content of 16.5 %)

Key value for chemical safety assessment

EC50 for freshwater algae:

0.55 mg/L

EC10 or NOEC for freshwater algae:

0.17 mg/L

Additional information

Read across - FF6:

The substance was tested in a study following OECD Guideline 201 and GLP. It is not acute toxic to algae.

E_bC₅₀(72h)= 300 mg/L

E_rC₅₀( 72h) = 315 mg/L

The source substance contains the major organic moieties of the target substance. Therefore, this study shows that no toxicity to algae can be attributed to the organic moieties of the target substance.

Read-across Zn-ion

The target substance contains 16.5 % Zn ions. Therefore, the hazard value for Zn ion is converted to the target substance considering a Zn content of 16.5 %.

De Schamphelaere, 2005

Zinc toxicity to a green alga (Pseudokirchneriella subcapitata) was evaluated in a series of experiments with spiked natural surface waters. The eight selected freshwater samples had varying levels of bioavailability modifying parameters: pH (5.7–8.4), dissolved organic carbon (DOC, 2.48–22.9 mg/L), Ca (1.5–80 mg/L), Mg (0.79–18 mg/L), and Na (3.8–120 mg/L). In those waters, chronic zinc toxicity (expressed as 10% effective concentrations [EC10]) varied up to 20-fold for the alga (72-h EC10 from 27.3 to 563 mg Zn/L). An increase in Ca, Mg, and Na concentraion and pH value had protective effects on the zinc toxicity, whereas the pH had the most significant effect. Both inorganic and organic Zn complexation reduces Zn²⁺ activity and thus also reduce toxicity. Inorganic complexation (i. e. ZnCO₃) is relatively straightforward, while dissolved organic matter (DOM) vary much in their zinc-binding characteristics. This result is also relevant for the target substance, which contains 16.5 % zinc ions. The EC50 values converted to the target substance range between 0.64 and 12.42 mg/L depending on the pH and DOC content.

Johnson 2007

Chlorella sp.was acclimated in medium containing 2 µg Cu/L for 100 days. Changes in algal growth rates and copper and zinc tolerance were monitored using standard growth inhibition toxicity tests in minimal medium over 72 h. The acclimated Chlorella sp. culture had no increased zinc tolerance compared with that of the nonacclimated algae, nor were there any changes in control growth rates. The IC50 of the non-acclimated culture was 110 µg Zn/L, whereas the culture acclimated to 2 µg Cu/L for 82 days showed an IC50 value of 98 µg Zn/L. The LOEC and NOEC for the non acclimated algae was 44 and 20 µg Zn/L, respectively. This result is also relevant for the target substance, which contains 16.5 % zinc ions.

Converted to the target substance under consideration of the zinc content of 16.5 %, the IC50 value is 0.55 mg/L, IC10 value is 0.17 mg/L, LOEC is 0.27 mg/L and the NOEC is 0.12 mg/L.